This invention relates to tool for CNC machine tools and more particularly to such a tool for finishing the side edges of flat workpieces supported on tables of CNC router machines.
In the prior art, there has been developed a CNC machine of the type shown in FIG. 1 which may by utilized to perform various machining operations on a workpiece supported thereon. Generally, the machine includes a base member 10, a table 11 supported on a set of guideways provided on the base member and displaceable longitudinally or along an x-axis, a bridge or gantry member 12, disposed transversely and above table 10, and supported on a pair of upright members 13 and 14 disposed astride the base member and usually connected thereto, a toolhead support assembly 15 supported on the bridge member and displaceable transversely or along a y-axis on set of guideways 16 and 17, and a toolhead assembly 18 supported on the toolhead support assembly and displaceable vertically along a z-axis. Worktable 11 is provided with a workpiece support surface 19 on which a flat workpiece or panel 20 may be mounted to be machined. The workpiece may be held on the worktable by means of either mechanical clamps or a vacuum system. In lieu of worktable 11 being displaceable along the x-axis and gantry 12 being stationary as shown in FIG. 1, work table 11 may be stationary and gantry 12 may be mounted on guideways provided on base member 10 and displaceable along the x-axis.
Toolhead assembly 18 is of a rotary turret type which may be indexed to position eight different powered tools 21 vertically or along the z-axis to perform various machining functions. The construction and operation of a machine as shown in FIG. 1 is described in greater detail in U.S. patent application, Ser. No. 08/701,315, filed Aug. 21, 1996, which is incorporated herein by reference. In lieu of a turret type of toolhead assembly, a conventional tool changer can be used which operates simply to position and attach selected tools to a single spindle of the toolhead assembly.
Typically, the various tools mountable on the rotary turret of the machine shown in FIG. 1 include a router, a shaper, a drill unit, an electric saw, a comer squaring tool and a profile edge sanding system. Such tools are usually driven by electric and air motors at speeds of up to 18,000 rpm. The machine further has a feed rate of up to 900 inches per minute although the actual feed rate will depend on the particular tool used, the material being machined, the pattern being cut and the finish desired.
In the use of the machine as described in forming an edge on a workpiece 20 which may consist of the top of a table, desk, bureau or other item of furniture, with the controller of the machine programmed and operating, the rotary turret will index to position a router tool of the desired profile into the vertical, operative position, and the servomotors operating the displacements of the table, tool head support assembly and toolhead assembly will be operated in accordance with the instructions of the program inputted into the controller of the machine to rout the edges of the workpiece supported on the table. When the routing operation has been completed, the rotary turret is indexed again to position the edge-sanding tool in the operative position to traverse the same path as the router tool to provide a sanded finish. In the past, such sanding tool has consisted of a lower, circular plate member, an upper circular plate member provided with a shank section mountable on the toolhead spindle and a sanding strip interposed between the upper and lower plate members and about the periphery thereof. Because of the configuration of such edge-sanding tools, it has been necessary to interrupt the machining sequence of such workpieces to elevate the workpieces relative to the table on which they are supported in order to permit such edge-sanding tools to be used without the lower plate members thereof engaging the worktable. Furthermore, because of the nature of the construction of such edge-sanding tools, they are required to be operated at much lower speeds, usually in the order of 1,800 rpm which require different motors than the other tools mounted on the rotary turret which normally operate at much higher speeds. Typically, such edge-sanding tools require 2 hp motors as compared to 9 hp motors for the other cutting tools of the turret.
The necessity of having to interrupt an edge forming and finishing operation to elevate the workpiece after the routing stage of the operation, the requirement of a motor different than the motors of the other tools mounted on the rotary turret and the low operating speeds of such conventional edge-sanding tools has had the effect of not only increasing the cost of manufacture of such machines but reducing their productivity. It thus has been found to be desirable to provide an edge finishing tool for the type of machine described which would obviate such problems attendant to prior art edge finishing tools.
The present invention obviates the aforementioned shortcomings of conventional edge finishing tools by providing a tool mountable on a high speed spindle of a CNC machine tool, operable to finish a side edge of a flat workpiece positioned on a support surface of the machine tool, generally consisting of a member having a shank section removeably mountable on the spindle of the toolhead assembly of the machine, and a head section. The head section is provided with an annular side surface engageable with the side edge of the workpiece positioned directly on the support surface of the machine. The annular surface is provided with a profile corresponding to the profile of the side edge of the workpiece, and abrasive particles bonded to such surface.